Population assessment of redhorse (Moxostoma Spp.) in the upper Oconaluftee River, Qualla Boundary, NC

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Ethan Andrew Fite (Creator)
Institution
Western Carolina University (WCU )
Web Site: http://library.wcu.edu/
Advisor
Thomas Martin

Abstract: The Oconaluftee River is a moderate to large sized stream located in the Little Tennessee River basin of the southern Appalachian Mountains. The Little Tennessee River basin is home to six different species of Redhorse, three of which, Black (Moxostoma duquesnii), Golden (M. erythrurum), and Sicklefin (M. sp.), are thought to have historically occurred in the section of the Oconaluftee River above Bryson Dam near the mouth of the River. Despite propagation efforts and restorative stocking of the extirpated Sicklefin Redhorse population, there has been no sign of success. Understanding of rare species (such as the Sicklefin Redhorse) has been a priority for researchers; however, other Redhorse species are understudied in the southern Appalachian Mountain region. Increasing the overall knowledge of other Redhorse populations in areas where Sicklefin Redhorse have been extirpated provides vital information on ability of the habitat to support Redhorse populations. From April to September of 2017, we used fyke netting and mark-recapture electrofishing surveys to assess Redhorse population abundance and demographics in the upper Oconaluftee River. Due to high flows and interference from otters, we determined that the fyke net was unsuitable for sampling in this system. Using the raft electrofishing system, we captured 624 Black Redhorse aged 1-12 and 138 Golden Redhorse aged 1-10. No Sicklefin Redhorse were captured during our sampling events. Population abundance of the sampled reaches for Black Redhorse was estimated at n=2101 (Schumacher-Eschmeyer) or n = 1357 (Cormack-Jolly-Seber) and Golden Redhorse was estimated at n = 1084 (Schumacher-Eschmeyer) and too few recaptures occurred to estimate using the Cormack-Jolly-Seber model. Two distinctive size classes were found for both species of Redhorse, which were grouped largely by age. Only one individual was aged at 4 years for Golden Redhorse, perhaps indicating a failed year class for the population or failure to capture Redhorse in that year class. Using life-table modeling, the Black Redhorse population in the upper Oconaluftee system was estimated to be slightly increasing. Electrofishing surveys were most efficient at lower discharge levels for capturing Redhorse. The von Bertalanffy growth models show similar parameters to those from other Southern Appalachian populations as well as Black Redhorse populations in Canada. Weekly larval fish samples were taken from April to August 2017 using drift nets and light traps to assess Redhorse reproductive occurrence and reproductive output. Larval catostomids were captured at all sampling locations with the majority (>70%) being identified as Moxostoma, indicating that there are reproducing Redhorse populations throughout the entire upper Oconaluftee system. There was a significant difference in sample location, with the middle sample site having the highest drift density (Mean drift densities for each site from 4/26/17-6/4/17: Up=7.54 x 10-3 larvae/m3, Mid=2.93 x 10-2 larvae/m3, Low=3.10 x 10-3 larvae/m3).

Additional Information

Publication
Thesis
Language: English
Date: 2018
Keywords
Black, Cherokee, Golden, Oconaluftee, Redhorse, Sicklefin

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